The closer an amphibian moved toward a beetle larva, the more wildly the larva moved its antennae up and down or from side to side. Some larvae opened and closed their thorny mandibles while waving their antennae.
The dance of mouth parts seemed to lure amphibians into attacking.
“Amphibians hunt by movement,” Wizen said. “They’ll generally go after anything that’s small, moving, and within their reach.”
When an amphibian shot out its lightning-fast tongue to eat a larva, the larva quickly bobbed its head to dodge the attack. Moments later, the larva latched onto its prey’s skin and began to suck it dry.
In attacks by 420 beetle larva, about 70 percent used a luring dance. No amphibian, however, successfully killed a larva.
Seven amphibians did capture a larva in their mouth, but each quickly spat them out. The mistake cost the amphibians their lives. Each larva recovered, latched on and ultimately ate the amphibian.
One amphibian did hold a larva in its stomach for two hours, but eventually regurgitated it. That amphibian was also eaten by the larva. (Wizen, G. et al. 2005)